In some communication systems, base stations transmit beam-formed transmissions to communication terminals by applying a precoding operation to the signals prior to transmission. In addition, the base stations transmit Reference Signals (RS) to the terminals, for example in order to enable the terminals to estimate the response of the communication channel.
Precoding and RS transmission are used, for example, in Evolved Universal Terrestrial Radio Access (E-UTRA) systems, also referred to as Long Term Evolution (LTE) or LTE-Advanced (LTE-A). Precoding and RS transmission for E-UTRA are specified, for example, in “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10),” 3GPP TS 36.211, version 10.3.0, September, 2011; and in “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (Release 10),” 3GPP TS 36.212, version 10.3.0, September, 2011, which are incorporated herein by reference.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.